Factors influencing G-CSF-mediated mobilization of hematopoietic progenitor cells during steady-state hematopoiesis in patients with malignant lymphoma and multiple myeloma

We retrospectively analyzed factors influencing PBPC mobilization during steady-state hematopoiesis in 52 patients with malignant lymphoma (n = 35) or multiple myeloma (n = 17) who received 77 cycles of G-CSF (12.5-50 mu g G-CSF/kg/day). For 15 of these patients, the first mobilization cycle (12.5 mu g G-CSF/kg/day) was followed by a second course with an increased dose of G-CSF (25 or 50 mu g/kg/day). Leukapheresis was started on day 4, about 2 h after s.c. G-CSF administration, and repeated on 2-5 consecutive days. CD34+ cells were determined by flow cytometry in each apheresis product and in the peripheral blood prior to G-CSF administration. beginning on day 4. Colony assays were performed on cryopreserved samples prior to autografting. In the 15 patients receiving two mobilization cycles the higher G-CSF dose was associated with higher levels of CD34 + cells, a higher mean yield of CD34 + cells per apheresis (p < 0.05), and a higher percentage of successful (>2 x 10(6) CD34+ cells/kg) collections (p = 0.058). Patients with limited previous cytotoxic therapy (n = 19, up to six cycles of a standard regimen such as CHOP and/or less than 20% marrow irradiation) who received a daily dose of 12.5 mu g G-CSF/kg had higher levels of circulating CD34 + cells, a higher mean yield of CD34 + cells per apheresis (p < 0.05), and a higher percentage of successful collections (p < 0.05) compared with patients previously treated with more intensive radiochemotherapy (n = 15). Ten of 20 patients (50%) who failed during the first cycle were successful during subsequent cycles with escalated doses of G-CSF. Trough levels of circulating CD34 + cells on day 4 were predictive for success or failure to achieve >2 x 10(6) CD34 + cells/kg, especially in heavily pretreated patients. Tn conclusion, a daily dose of 12.5 mu g G-CSF/kg seems sufficient to mobilize PBPC during steady-stare hematopoiesis in the majority of patients who have received limited previous radiochemotherapy. Higher doses of G-CSF, up to 50 mu g/kg/day, mobilize more PBPC and should be considered for patients previously treated with intensive radiochemotherapy or those failing to mobilize sufficient numbers of CD34 + cells with lower doses of G-CSF.